aplastic anemian. A form of anemia in which the capacity of the bone marrow to generate red blood cells is defective, caused by bone marrow disease or exposure to toxic agents, such as radiation, chemicals, or drugs.

(ā-plās'tĭk) A form of anemia in which the capacity of the bone marrow to generate red blood cells is defective. Aplastic anemia may be caused by bone marrow disease or exposure to toxic agents, such as radiation, chemicals, or drugs.